DCC Question?

Discussion in 'FAQs' started by kf4jqd, Feb 1, 2004.

  1. kf4jqd

    kf4jqd Active Member


    I have a DCC question. Can I install DCC into any locomotive at any scale? I have a new Spectrum and used Life Like Nscale locomotives. Can I any to them?

    What about my HO scale locomotives? I have Athearn, Stewart, and Spectrum, and Walthers. Can I add any to them? Are there any locomotives I should advoid for DCC?

  2. Matthyro

    Matthyro Will always be re-membered

    As long as there is room for the decoder and wiring then you should be able to install a decoder in almost any loco. Some you may have to remove some of the weight to make room.
    Some locos come ready for a decoder so it's just plug and play. Much depends on the decoder and loco you have.
    The decoder should be able to handle the amperage your loco needs so for larger scales check that the decoder can handle the power
  3. Russ Bellinis

    Russ Bellinis Active Member

    One other thing with adding dcc to older locomotives. It is my understanding that the motor should be isolated from the frame. You want the decoder to pick up track voltage, but the motor should get it's voltage and polarity from the decoder only. In the case of Athearn, you will need to remove the motor from the locomotive and reverse the clips that hold the motor together to get the brass clip that normally grounds to the frame off of the bottom of the motor. In the case of Bachmann Spectrum and Bachmann plus as well as some early Lifelike P2K, I think they were built like n scale locomotives with the frame halves on either side of the motor with the motor contacts making contact with each frame half. I think it is again necessary to insulate the motor from the frame halves so that it only gets power and olarity from the decoder as well.
  4. shaygetz

    shaygetz Active Member

    Russ is right, the two hardest things about installing DCC is;

    1. You have to isolate the motor from the frame. Not too mean a trick on Athearns and Rivarossi but some may not be worth the effort necessary. Weigh it out as you go.

    2. Amps, amps, amps. By now somebody's got a chart to go by or something to help. Your older equipment is really the only place to worry about as most newer stuff has more efficient, low draw motors. When all else fails, err on the side of caution and use higher rated decoders on older equipment.
  5. kf4jqd

    kf4jqd Active Member

    Did I get this right?

    Ok, let me get this right. The motor needs to be shielded and the amps. If the layout is 6' x 40', do I need a booster? Hopefully my 1500 watt Ham Radio station will not interfer, but the antennas will be a couple of 100 feet away from the house.

  6. shaygetz

    shaygetz Active Member

    Re: Did I get this right?

    Not shielded---isolated. The motor should only draw its power from the decoder. Our 6x90 club layout has 2 power stations, one with an 8 amp transformer, one with a 6 amp one. We have extra radio transmitters so that there are no "blind" spots for our throttles. We are next to a courthouse and a sherriff's station and have noticed no interference from their transmissions.
  7. 60103

    60103 Pooh Bah

    If you can stay with locos that have 2 wires between the wheels and the motor brushes, you are OK. When you have only one wire and the other side is in the frame, you have some work to do.

    I have some British locos where the frame is not only the circuit but also forms the motor frame (one BIG casting) and one brush is mounted in and fed through the frame. This is next to impossible to do (But Herr Lenz said he has something coming up!)
  8. railwaybob

    railwaybob Member

    Insulating Athearn motors is very simple. Remove the plastic shell. Remove the copper clip on top of the motor. Make sure you don't lose the spring and motor brush! Get rid of the light.

    Push out the 4 white plastic lugs on the underside of the frame that hold the motor in place. Remove the copper clip on the bottom of the motor and break off the copper tab that hangs down from the copper strip (the copper tab touches the bottom of the metal frame.

    Place a piece of electrical tape on the bottom of the frame between the two white plastic tabs that fit into each side of the motor. This will insulate the motor from the frame.

    Solder a piece of wire to the bottom copper clip. This is one of the motor wires that will be connected to your decoder. Replace the bottom copper clip, replace the motor.

    Solder a piece of wire to the top copper clip. This is one of the motor wires that will be connected to your decoder. Replace the motor spring, motor brush, and top copper clip.

    Follow the instructions for installing your decoder. If you're still not sure of how to do it, get a Digitrax Athearn wiring kit.

    But make sure you place that electrical tape on the bottom of the frame (that's one step in the instructions that's missing)!
  9. zeeglen

    zeeglen Member

    Re: Did I get this right?

    Andy, this is a good question. Has anybody ever tried operating powerful shortwave radio transmitters near a DCC-equipped railroad? There may be an incompatibility here, especially if track and wire lengths happen to resonate at the transmission frequency. Keep us posted if this turns out to be a problem or not. -glen, ex VE4GC
  10. Matthyro

    Matthyro Will always be re-membered

  11. Fred_M

    Fred_M Guest

    I may be out of line here, but why would a 1500 watt transmitter affect a dcc train anymore than a radio, tv, computer, or garage door opener? Back in the 1960's them transmitters were dirty and would mess with peoples TVs and radios for miles around (the offending party always blamed their neighbors"cheap TVs") and they were running 600 and 700 watts. But do today's transmitters interfere with TVs or other items? I haven't noticed it myself for over 20 or 30 years. FRED
  12. zeeglen

    zeeglen Member

    No, you are not out of line. This is another darn good question, and i will try to answer as best i can. Remember, i have not seen this problem either, but i don't run DCC or a ham radio station any more and am wondering if it actually could be a problem.

    Big differences today. Most TVs are now operated from shielded cable (CATV) instead of fringe-area antennas which were sitting ducks for local high power ham transmitters. And as a result of this TVI the filtering and front end dynamic range in TV and other receivers had to improve, so today's TV sets are far more able to reject out of band signals. And yes, a lot of the old ham transmitters, especially the home brewed ones, were 'dirty' and did emit signals in the TV portion of the spectrum. Today's commercially made ham transmitters are likewise improved to limit this.

    Computers are well shielded nowadays to prevent them from interfering with TVs. (Remember the old TRS80 and the TV interference it caused?). By the same token, if computers can't emit their internal noise, they also reject external signals by nature of this same shielding and cable filtering.

    DCC signals are relatively slow rise/fall times and don't emit much interference in spite of the big antenna they are connected to (aka the railroad track and wiring) and so do not need filtering to prevent TV interference. But this unshielded railroad track works as a receiving antenna too, and with little or no RF filtering the radio signals from near-by high power transmitters can induce strong electric currents and voltages in the railroad track and wiring. When wire and track lengths are tuned randomly by their length (odd multiples of a quarter wavelength - typically 8' at 10 meters, 16' at 20 meters etc) to specific radio frequencies they can develop much higher than usual voltages at the ungrounded ends. This voltage is the same on both rails (assuming twisted pair wires to the tracks and both rails isolated at electrical gaps) so the question of whether or not it will bother the digital logic inside a decoder or booster is the unknown. Common rail wiring could be much worse since these radio voltages are not cancelled by symmetric and balanced cabling.

    It's just something to be aware of, and since Andy (KF4JQD) is in a position to try this out it could be useful to know he observes any bad effects.
  13. jon-monon

    jon-monon Active Member

    A big bright green sign went up last week, at the crossing on the edge of the local NS yards. It indicates the trains are being run by remote control and may be unmanned. I'll bet if Ham, CB's or anything else messes with their signals, they'll get to the bottom of it fast! :D :D :D 1:1 train set!
  14. CN1

    CN1 Active Member

    Don't expect any problems

    It's not so much the transmitter but the receiver that maters. If the antennas is very close to the transmitting sources and the frequency is almost overlapping you may get interference.

    The CRTC and the US equivalent have strict rules about frequency interference and frequency spacing. Since DCC is approved by both I would be very surprise if any type of interference could be caused by ham radio or the like..
  15. zeeglen

    zeeglen Member

    Re: Don't expect any problems

    The strict rules by the FCC (USA), VDE (Germany/Europe), etc are intended to protect radio and TV (and police, fire, aircraft etc) communications from inadvertent interference due to radio emissions from digital electronic equipment, which includes computers and of course DCC. The fast transistions of the digital logic create these emission as a natural byproduct, and great lengths are taken to prevent the escape of the resulting radio energy to the outside world. Note the standard FCC Part 15 labelling on any piece of digital equipment designed for residential use which includes a phrase to the effect 'this equipment must accept any interference from ...'

    In other words, regulatory agencies protect the communications function of the electromagnetic spectrum. They do not care if a licensed and legal radio transmitter causes a piece of digital equipment to react unfavourably in the presence of a strong radio energy field. The onus is on the design of the digital equipment to continue to work in spite of being in a strong radio field.

    Horror stories from the past abound - an electric wheelchair driving itself (and it's owner) off a cliff when a nearby CB radio was keyed on. Vehicle brakes locking up on a freeway when the adjacent vehicle turned on a radio transmitter. Blasting caps setting off a load of dynamite prematurely for similar reasons. A pacemaker user keeling over when keying on a 2 meter ham radio transmitter. Urban legends? Maybe. But the potential for this kind of interference is always present. That's why airlines tell their passengers to turn off all digital equipment (cellphones, digital cameras, CD players) during take-off and landing.

    We don't hear about this much these days because the occasional problems that surfaced in the past resulted in design improvements to cure these problems. DCC is not a life-and-death situation, and it is unlikely that turning on your cellphone will cause your prized locomotive to hurl itself off the end of a siding and over a cliff onto the floor. But 1500 watts of radio energy is a lot - will quickly cook a hot dog in a microwave oven - and this kind of power can have other unforseen effects when located close to digital equipment that is by nature unshielded from ambient radio energy.

    So for any hobbyists that enjoy both DCC railroading and ham radio, have you noted any interaction between the two? Generally this type of hobbyist will indulge in one hobby at a time, but what happens when two neighbours (a ham radio operator and DCC model railroader) get to doing their own thing at the same time?

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